Study: Diet Soda May Not Raise Risk of Diabetes After All

Previous studies have linked drinking diet soda with a higher risk of diabetes, among other health problems. But a large, long-term study bucks the trend, suggesting that diet sodas and other artificially sweetened drinks won’t raise your chance of developing diabetes after all.

Though past studies have suggested that people who regularly drink diet soda may be at higher risk of developing diabetes than non-soda-drinkers, that association may have more to do with the type of person who drinks diet soda to begin with — not the diet soda itself. People who are overweight or already at risk for diabetes may be more likely than others to drink diet soda, the authors of the new study suggest.

The study, led by Dr. Frank Hu, professor of nutrition and epidemiology at Harvard School of Public Health, followed more than 40,000 men for 20 years, from 1986 to 2006. Participants were asked to fill out regular questionnaires about their medical conditions and dietary habits, including the amount of diet soda and other beverages they drank. About 7% of the men reported being diagnosed with diabetes during the course of the study. Men who drank the most sugary drinks — about one serving a day — were 16% more likely to be diagnosed with diabetes than men who stayed away from these drinks. The increase was associated mainly with carbonated sugary drinks, but not other sweet beverages like lemonade, the study found.

After the researchers controlled for other diabetes risk factors in the men, including weight, blood pressure and cholesterol, they found no association between diet soda and diabetes risk. Drinking coffee or tea regularly also did not increase risk of diabetes; in fact, men who drank regular or decaf coffee daily had a lower risk of the disease.

That finding is “confirming the idea that it’s really these differences between people who choose to, versus don’t choose to, drink artificially-sweetened beverages” that is related to diabetes, Dr. Rebecca Brown, an endocrinologist at the National Institutes of Health, told Reuters Health. “People who are at risk for diabetes or obesity … those may be the people who are more likely to choose artificial sweeteners because they may be more likely to be dieting.”

So is diet soda O.K. to drink? “There are multiple alternatives to regular soda,” Hu told Reuters Health. “Diet soda is perhaps not the best alternative, but moderate consumption is not going to have appreciable harmful effects.”